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<p>[QUOTE=&quot;GDJMSP, post: 2765221, member: 112&quot;]In the end does it really matter if grease is a solid or a liquid ? What I mean is this, grease is absolutely different than water because of its viscosity. And even if the end result a coin being struck through water is similar in some ways to one that is struck through grease, it&#039;s going to be somewhat different, and maybe very different at least in some cases, as a result of that viscosity. Here&#039;s why.</p><p><br /></p><p>First forget the science part of it and think about the common sense part of it. Water and grease both, if pressure is exerted on them between 2 soild objects, will be squeezed out. Maybe not 100% squeezed out but the majority of it will be. And if you think that won&#039;t happen then think again.</p><p><br /></p><p>You guys know what finning is don&#039;t you ? Finning occurs when a coin is struck with too much pressure. As a result of that excess pressure, a solid, the metal of the coin planchet, is squeezed out in the tiny gap that exists between the planchet, the dies and the collar. This solid is literally pushed up through that tiny gap so that it remains and a thin fin is attached to the rim of the struck coin. So, if this can happen to a solid, and there can be no argument that the metal is a solid, what do you think would happen to grease or water ? And this happens purely because of pressure, and it doesn&#039;t matter if it&#039;s a solid or a liquid - it still happens. And rather obviously it&#039;s going to take less pressure for it to happen with water or grease than it does with metal.</p><p><br /></p><p>The question then becomes why then does grease affect a coin the way it does when that coin is struck through grease ? The obvious answer is because it is a substance that is between the dies and the planchet, and any substance that is between them is going to have some effect. No matter what it is it&#039;s not going to be like it wasn&#039;t there. And that&#039;s where the difference in the viscosity of grease and water comes into play. While both water and grease can have particles of other substances like dirt and tiny metal particles suspended within them, because of its high viscosity grease is almost certainly going to have more of them than water will. Grease is stuck there on the parts of the press allowing more and more particles of other substances to become stuck in that grease over time. With water that&#039;s not as likely to happen because most particles that get into the water settle out very quickly and with grease they don&#039;t.</p><p><br /></p><p>So, if a blob of grease happens to fall on a die, the particles that are stuck to and in that grease go with it. And when the coin is struck most of the grease will be squeezed out but some of those particles are going to remain behind because they won&#039;t move as quickly as the grease does. And those particles and the remaining grease both affect how the coin will look. In effect the particles are strike-throughs, many of them, but so tiny that you can&#039;t differentiate one from the other. And whatever remains of the grease is too.</p><p><br /></p><p>But if a drop of water falls on a die, which is pretty unlikely to begin with but for the sake of argument we&#039;ll say one does, it&#039;s not going to contain as many particles as the grease does. Sure, it will still have an effect on the struck coin, but it&#039;s not going to be as pronounced as the grease is.</p><p><br /></p><p>Now all of that&#039;s just common sense, not a whole lot of science really involved. But you could add the science in there if you wanted to, you could measure the weight of the grease and water, measure the viscosity, the size and weight of the particles, the principles of adhesion, the compression factors of all substances involved, and all the other stuff that I don&#039;t even know about. But in the end it&#039;s gonna be the same thing. The grease will have more effect than the water does. It&#039;s merely a matter of degree.[/QUOTE]</p><p><br /></p>

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